The present invention generally relates to zoom lenses, and more particularly to a zoom lens which can be used as a photographic lens of a camera with a diaphragm shutter or as a lens in a video camera.
In general, there is a demand for a high-power zoom lens in a camera with a diaphragm shutter. Recently, a variable power ratio of greater than 2.5 is demanded. As cameras having a compact size are produced, a zoom lens with a compact size is demanded.
The fewer the movable lens groups, the better a zoom lens is from the view points of compactness of the zoom lens and simplification of a zoom mechanism. The Japanese Laid-Open Patent Application 2-50118 discloses a construction in which there are only two movable lens groups, and by which the variable power ratio of greater than 2.5 is achieved. However, this construction is far from being ideal in that there are as many as 10-11 lenses. Another problem is that the lenses near the image surface are large because the back focus is extremely short. Hence, such a conventional construction does not fulfil the demand of making the zoom lens more compact.